Fixes in DO extractText function. refs #8147
Fixes in DO extractText function. refs #8147

- Create new temporary copy from external resources if the old copy is missing
- Stop if the local copy is missing before calling 'pdftotext'
- Do not duplicate the DO 'transcript' property

Surfrdan/atom,artefactual/atom,CENDARI/atom,Surfrdan/atom,CENDARI/atom,Surfrdan/atom,CENDARI/atom,artefactual/atom,artefactual/atom